THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[18:00:00] WOLF BLITZER, CNN ANCHOR: Donald Trump has just responded to Paul Ryan. What is he saying? Stand by.

Staying home with the party in disarray. Top Republicans now say they're skipping the convention, including the last two Republican presidents and last two Republican presidential nominees. Will the Trump train arrive in Cleveland half empty?

Blindsided. Stunning new video of a firefight with ISIS that killed an American Navy SEAL the Pentagon making an extraordinary admission. Did SEALs have access to all the intelligence they need?

And straw buyers. Investigators are looking into weather Prince's inner circle may have obtained drugs. Why are federal agents involved in the probe?

We want to welcome our viewers in the United States and around the world. I'm Wolf Blitzer and you're in THE SITUATION ROOM.

(MUSIC)

ANNOUNCER: This is CNN breaking news.

BLITZER: We are following breaking news right now. The country's highest ranking Republican publicly rejecting the party's presumptive nominee, Donald Trump. House Speaker Paul Ryan telling CNN's Jake Tapper in an exclusive interview that he is not ready to endorse Trump, at least not yet.

It's the most striking sign so far of the deep division Trump's campaign created within the GOP. Trump responded with a carefully drafted statement saying he's not ready to support Speaker Ryan's agenda.

Trump is about to hold a rally in West Virginia, we are standing by to see what he will say about these extraordinary developments.

We are covering that and more this hour with our guests, including Republican National Committee's chief strategist and communication director, Sean Spicer, and our correspondents and expert analys, they are also standing by.

This is a remarkable admission. Speaker of the House Paul Ryan coming out now and saying he's just not ready to support Donald Trump yet, it really underscores how much of a war is still raging on between Donald Trump and factions of his own party.

(BEGIN VIDEOTAPE)

SERFATY (voice-over): Donald Trump is facing a new wave of resistance within his own party. House Speaker Paul Ryan speaking out today with the first time since Trump became the presumptive nominee in an exclusive interview with CNN's Jake Tapper.

JAKE TAPPER, CNN ANCHOR: Now you have a presumptive nominee, Donald Trump, will you support him?

REP. PAUL RYAN (R-WI), SPEAKER OF THE HOUSE: Well, to be perfectly candid with you, Jake, I'm just not ready to do that, at this point. I'm not there right now and I hope to though and I want to. But I think what is required is that we unify this party. I think the bulk of the burden on unifying the party will have to come from the presumptive nominee.

SERFATY: Ryan admitting there's a lot of work to be done.

RYAN: And we've got ways to go from here to there.

SERFATY: This as four of the last five presidential nominees are now skipping the GOP convention.

DONALD TRUMP (R), PRESIDENTIAL CANDIDATE: I went through a rough primary where I was harsh on some people like Jeb Bush and, you know, you wonder why the Bush family wants to sit it out. When I hear they want to sit it out, I think that's fine. I don't care if they sit it out.

SERFATY: Add that to some prominent Never Trump Republicans who are now working in overdrive to find a third party candidate to run against him.

BEN HOWE, CONTRIBUTING EDITOR, REDSTATE.COM: In my opinion, it's not over. We can stop him and I would like to.

SERFATY: Nebraska Republican Senator Ben Sasse with this open letter, asking of those who say their only choice is Trump or Clinton, why is that the only choice.

Sasse calling for voters to rally around a third party candidate, writing, "I think there's room, an appetite for such a candidate." But the problem no such candidate has stepped up yet.

RYAN: I do not want, nor will I accept the nomination for our party. SERFATY: Meantime, some panic is setting in about Trump's potential

effect on down ballot candidates, expressing concerns at a closed door fund-raiser according to a recording obtained by CNN.

SEN. JOHN MCCAIN (R), ARIZONA: Donald Trump at the top of the ticket in Arizona with 30 percent of the vote being Hispanic vote, no doubt this may be the race of my life.

SERFATY: But Trump in an interview with Wolf is signaling he is moving forward.

TRUMP: Essentially started. I mean, yes, started today, started actually three months ago when I hit her pretty hard and she went down.

SERFATY: Among the items on his to-do list, organize a list of vice presidential options.

TRUMP: I think in terms of vice president I am going to go the political route, I don't need the business route. I have that covered.

SERFATY: Trump is shooting down some names being floated.

TRUMP: No, not Nikki Haley.

[18:05:00] Nikki Haley, no, she wasn't under consideration.

SERFATY: But indicating openness to some former rivals.

TRUMP: Marco is a good guy, a really nice guy, and I like him. But not necessarily with respect to any position, but it could happen.

SERFATY: And announcing today his national finance chairman building out a funding operation for the general election fight ahead, but not losing his provocative touch on Twitter, for Cinco de Mayo. Tweeting, quote, "The best taco bowls are made in Trump Tower Grill. I love Hispanics."

(END VIDEOTAPE)

SERFATY: And as Donald Trump tries to consolidate support within the party, sources tell CNN that Trump's campaign met today with roughly a dozen top aides on Capitol Hill and are working on setting up a meeting for Donald Trump and some key congressional Republicans soon. But as of now, Wolf, no date for that meeting that has been set.

BLITZER: That takes place with Trump and Paul Ryan.

Sunlen Serfaty, thanks very much.

Right now, I want to listen a little bit to more to what the House Speaker Paul Ryan told CNN's Jake Tapper about Donald Trump in that exclusive interview as he explained why he's not yet ready to support Donald Trump.

(BEGIN VIDEO CLIP)

RYAN: I don't want to underplay what he accomplished. He needs to be congratulated for an enormously accomplishment, for winning a plurality of delegates and he's on the way to winning majority of delegates. But he also inherits some thing very special, that's very special to a lot of us. This is the party of Lincoln, of Reagan, of Jack Kemp, and we don't always nominate a Lincoln and a Reagan every four years.

But we hope our nominee as far as being Lincoln and Reaganesque, that that person advances the principles of our party and appeals to a vast majority of Americans. I think what's necessary to make this work for this to unify is to take our principles and advance them and that's what we want to see. Saying we're unified doesn't in and of itself unify us, but actually taking principles we all believe in, showing that there's a dedication to those, running a principled campaign Republicans can be proud about and that can actually appeal to a majority of Americans, that to me is what it takes to unify this party.

TAPPER: So, you're saying you can't support or endorse him right now?

RYAN: Yes, I am basically saying that. You know, I thought about this two days ago. I thought actually this thing was going to go to June 7th at very least, probably to a convention. So, this is all pretty new for us, but at this point, I think that he needs to do more to unify the party, to bring all wings of the Republican Party together, and then to go forward and appeal to all Americans in every walk of life, every background, a majority of independents and discerning Democrats.

So, I think conservatives want to know, does he share our values and our principles on limited government, the proper role of the executive, adherence to the Constitution, there are questions that conservatives want answers to, myself included and I want to be part of this unifying process. I want to help unify this party, but we have to unite I think for us to be successful, first to have a campaign that you're proud of going forward that is unifiable and that can appeal to a vast majority of Americans.

TAPPER: Well, Mr. Speaker, you're casting this in characteristically optimistic and positive terms, I would expect no les from you. But what you're saying is a fairly dramatic announcement that speaker of the House cannot as of now support his party's nominee for president.

Is there something specific that he has done or said that has brought you to this moment?

RYAN: Well, like I said, I hope to support our nominee. I hope to support his candidacy fully, and I want to do that. But right now, I have to tell you, just being candid with you, at this point, I'm just not there now and it is because of part of the last campaign.

I don't want to go back and roll the tape. Look, I was pretty clear and I was outspoken on a number of occasions where I think he did the wrong thing and said the wrong thing. I will do it in the future if need be, I hope it is not necessary. But I think what a lot of Republicans want to see is that we have a standard bearer that bears our standards and that unifies all the wings of the Republican Party, which we all come from different wings of our party, but we all agree on a common platform of conservative principles.

We want somebody who takes these principles, applies them to the problems and offers solutions that a vast majority of Americans can vote for and be enthusiastic about. That's what I think it takes to unify the party. That I think there's work that needs to be done in order to do to unify the party. I think our nominee, our presumptive nominee needs to do that. I want to be part of helping him do that. But right now no, I think there's some work to do here.

(END VIDEO CLIP)

BLITZER: This important note, that full interview with Paul Ryan, Jake's full interview will air later tonight at 9:00 p.m. Eastern on "AC360", 9:00 p.m. Eastern.

Let's bring in our CNN political reporter Sara Murray right now. She's over at the Donald Trump rally that's about to get under way in West Virginia.

Standing by, we want to hear what Donald Trump actually has to say, but I understand he just released a formal statement.

SARA MURRAY, CNN POLITICAL REPORTER: That's right, Wolf, the Trump campaign did something rare, preempt Donald Trump on the stump, he put out a statement in response to Paul Ryan saying "I'm not ready to support Trump", saying, "I am not ready to support Speaker Ryan's agenda. Perhaps in the future we can work together and come to an agreement about what is best for the American people. They have been treated so badly for so long that it is time for politicians to put them first."

So, I think, Wolf, what you're seeing here is some of these divisions between what Donald Trump has done on the trail in terms of trade, in terms of the Muslim ban, and even in recent days when he is the presumptive nominee, he is doubling down, not backing away. And I think that's going to continue to potentially drive a rift between them even as the Trump campaign tries to consolidate more establishment Republican support behind his candidacy -- Wolf.

BLITZER: Pretty rebuke to the speaker of the House from Donald Trump, the Republican presumptive presidential nominee.

All right. Sara, we are standing by, fairly soon, he's going to be speaking. We'll, of course, be anxious to hear what else he says. Sara Murray is in West Virginia for us right now.

As we await more reaction from Donald Trump, let's get more on the breaking news now. Joining us, Republican National Committee chief strategist and communications director, Sean Spicer.

BLITZER: This is a pretty remarkable development right now. You speak for the Republican National Committee. Were you stunned, a, when speaker of the House at 4:00 p.m. Eastern told Jake Tapper he's not ready to endorse Donald Trump, and now, were you once again stunned when Donald Trump retaliated, if you will, by saying, "I'm not yet ready to support Speaker Ryan's agenda"?

SPICER: Look, it's been a remarkable week all around. We started off the week focusing on Indiana. A lot of people tried to figure out what the outcome of Indiana would be and how far the race would go. You've heard me say before, and I think Speaker Ryan echoed that, that everyone anticipated this race would go to June 7th because Donald Trump won't be the presumptive nominee officially until then.

So, there was a lot of -- no one was anticipating the week we had, Ted Cruz would drop out, subsequently, Governor Kasich would drop out of the race. So, I think for a lot of people and Speaker Ryan echoed that in his comments. We are anticipating having to deal with this issue. Mr. Trump talked about election night, I didn't anticipate this night, this isn't where I expected to be tonight.

BLITZER: But you guys didn't wait at all to declare he's the presumptive --

SPICER: I mean, again, that was math --

(CROSSTALK)

BLITZER: It's the same night that he won Indiana.

SPICER: There was a reality facing us, when Senator Cruz wasn't continuing, the math became obvious. We wanted to be sure we partnered quick as possible, that we began the process of unifying the party, focus on the election, get our resources together, because unlike the Democrats who continue to go at it pretty epically, Bernie Sanders and Hillary Clinton will have to go to June because she hasn't been able to breakaway from Senator Sanders.

BLITZER: But you've got to admit, this is pretty amazing.

(CROSSTALK)

BLITZER: Let me ask you a question, because I covered politics a long time.

SPICER: I know.

BLITZER: When you have a presumptive nominee from either party, that person quickly becomes the leader of that party. Is Donald Trump for all practical purposes the leader of that party? SPICER: We have had a very historic cycle in the Republican Party.

We started the process, as you know, back in August of last year with 17 amazingly qualified candidates. So, the idea you can look at a previous cycle and say, this is how it is supposed to go is just not the case this cycle.

And so, we ended up with a lot of elbows being tossed, lot of bruises. I think what we've got to do right now, what Speaker Ryan, I think what Mr. Trump is talking about is getting folks together to start that unifying --

BLITZER: Why hasn't that happened? You open --

SPICER: It happened Tuesday night.

BLITZER: An open fight between Paul Ryan and Donald Trump.

SPICER: Tuesday night, Senator Cruz decided for the good of the party to step down and start allowing the party to unify. Governor Kasich did the following the next day. This is early in the process.

We've got plenty of time. The Democrats have a historic primary -- you know, a primary going back and forth.

BLITZER: But Republican voters across the country have spoken. They want Donald Trump to be the party's nominee.

SPICER: Yes. He won and deserves to be --

BLITZER: He is the party's nominee.

You would think, Sean, correct me if I'm wrong, after he is declared the presumptive nominee, the speaker of the House would reach out to him, Donald Trump would reach out, they would have a little dialogue, a little conversation before you have in effect a conflict.

SPICER: From what I understand, they're working on setting up a meeting next week to sit down and to start that process, that discussion that Speaker Ryan wants to have.

So, I think it's going to happen, as the speaker mentioned, I think he's going to get there. The speaker cares dearly about the party. Everything that you heard Paul Ryan talked about since he got in the Congress, all the way up through his vice president, you know, being part of the et last time, ascension to House Budget chairman, and House Ways and Means chairman, and now, speaker, he's always been to think big about the party.

[18:15:11] He cares deeply about the party.

BLITZER: Here's the question. They disagree clearly. Trump says you have to support my agenda. The speaker wants him to support his agenda. He made that abundantly clear. Who's the leader of the Republic Party right now? Would it be Paul Ryan or Donald Trump?

SPICER: It is not either or. Donald Trump will be the presumptive nominee of the party, OK? So, by de facto the largest voice out there.

Paul Ryan is speaker of the House, he's currently highest elected official. Mitch McConnell is the majority leader of the Senate. Reince Priebus is the chairman of the party. We've got a lot of amazing governors coast to coast, it is not one person, but, yes, is the presumptive nominee the biggest voice of the party, absolutely.

BLITZER: Did you guys have a heads up from the speaker that he was about to do this?

SPICER: I think you know well that Chairman Priebus and Speaker Ryan are good friends. They talk quite often.

BLITZER: Both from Wisconsin.

SPICER: They're both from Wisconsin.

BLITZER: Did he know the chairman that Paul Ryan was going to come out today and saying, I'm not yet ready to endorse Donald Trump?

SPICER: The chairman and Speaker Ryan have been talking about the speaker's concerns about endorsing him and what he was going to take to get him there. He was not aware he would be on CNN today and make the comments.

BLITZER: If he had known, would he have tried to talk him a lot of it, for the good of the party, because you guys need to unify.

SPICER: What the chairman wants to do is bring them together, my understanding that's going to happen because --

BLITZER: When?

SPICER: Huh?

BLITZER: When is that going to happen?

SPICER: My understanding is they're working on a date next week. The point is --

(CROSSTALK)

BLITZER: Is Reince Priebus the mediator?

SPICER: He's not a -- he is leader of the Republican National Committee. And what he's trying to do is to reach out to all people. You saw the tweet Tuesday night. It is time as a party, we unite and defeat Hillary Clinton.

We cannot have Hillary Clinton in the White House. This isn't just four years, for Republicans and conservatives, we have to understand spending decisions and nominations she will make to the court could last a generation and be irreversible.

BLITZER: This is what the speaker told Jake Tapper. "I want to know if Trump shares conservative values on limited government, proper role of the executive and adherence to the Constitution," to which Donald Trump replied perhaps, "I am not ready to support Speaker Ryan's agenda." That was his agenda. "I am not ready to support Speaker Ryan's agenda. Perhaps in the future we can work together and come to an agreement about what is best for the American people."

And then he takes this dig. And listen to this, he says, "They have been treated, the American people, so badly for so long that it is about time for politicians," I think he's referring to Paul Ryan, "to put them first."

SPICER: I'm glad they're going to sit down and talk next week.

BLITZER: Shouldn't they have talked before this?

SPICER: This was a fast paced primary, very intense. As you know, we had a lot of candidates in there. No one was anticipating that Tuesday night. Senator Cruz did a very honorable thing for the party and help to expedite it, and Governor Kasich followed up with it. I think we have time, that's the beauty of what we have on our side, as opposed to the Democrats who continue --

BLITZER: Because Paul Ryan says he wants to know if the leader, effective leader, the nominee, presumptive nominee Donald Trump accepts the adherence to the Constitution, if he's ready to accept adherence to the Constitution. That's a pretty, pretty dramatic statement.

SPICER: Like I said, it is good they'll sit down, have that conversation about where they stand on issues. Speaker can talk about his agenda and policy items he is putting forth to move the country in a positive direction, put people back to work --

BLITZER: What has to happen now?

SPICER: They need to sit down and have a talk.

BLITZER: Who is going to change?

SPICER: Huh? It's not a question of changing. It's about question about understanding.

BLITZER: Will Donald Trump have to walk away from the ban on all Muslims, walk away on the deportation of 11 million undocumented?

SPICER: It's not the question of walk away, that's not what the speaker said. I don't think you're going to have a question of you give up this. It is not compromising. It's a question of understanding.

What the speaker laid out was saying I need greater understanding of these issues from the nominee, and what clearly the nominee is saying is I would like to know more about your thing. I get it. It is fast paced environment that we've lived in right now. We have 17 candidates. It got whittled down quickly at the end. I think both of them however know they're committed to unifying the party. Look, one thing both of them further get, without a unified Republican

Party, we give Hillary Clinton a hand to get to the White House. And that's something that every Republican, every conservative should understand that not being unified results in greater chance of Hillary Clinton presidency.

BLITZER: We have a lot more to talk about. There are a lot of other divisions within the Republican Party that are emerging right now in the aftermath of Donald Trump becoming the presumptive nominee.

But I know Donald Trump, I've known him several years. And I -- my own gut tells me when he heard these words from Paul Ryan to Jake Tapper on CNN, he saw those words as a lack of respect for Donald Trump as the presumptive Republican nominee.

[18:20:06] That's why he responds this way.

But let's continue this conversation. Sean is not going anywhere. Much more with Sean Spicer right after this.

(COMMERCIAL BREAK)

BLITZER: Breaking news this hour: a stunning rebuke of Donald Trump by the highest ranking Republican in the U.S. government. In an exclusive interview with CNN's Jake Tapper, House Speaker Paul Ryan says he is not read yet to support Donald Trump as the Republican presidential nominee.

We are back with the Republican National Committee chief strategist and communications director, Sean Spicer.

[18:25:04] I just want to be precise, Sean. So, Reince Priebus, your boss, the chairman of the RNC, he is setting up a meeting between these two men, Paul Ryan, Donald Trump --

SPICER: He is not setting it up. The two individuals are setting it up themselves. He's not --

BLITZER: And they will be here in Washington?

SPICER: I don't know. That's between Speaker Ryan and Mr. Trump to figure out the details.

BLITZER: Who has to blink from this?

SPICER: Again, I don't believe that it is a question of who is blinking. I think it is a question of two individuals sitting down, gaining a greater understanding of the questions they have about each other. Frankly, Mr. Trump as an individual hasn't run for public office. He brought it up in the interview last night.

So, I think a lot of it is understanding the speaker's policy agenda, and the speaker needs to ask him questions where he stands on key issues that are important to him and House Republican conference.

BLITZER: Would seem like Reince Priebus would be a good intermediary. SPICER: He's close to both, don't get me wrong.

BLITZER: He's close to Paul Ryan. He's the leader of the Republican National Committee --

SPICER: He has been in contact with both, but he has also -- you know, they connected and --

BLITZER: Do you see it as a crisis now?

SPICER: No, I don't.

BLITZER: How would you describe it?

SPICER: Look, we entered a week no one thought we were going to. Nobody woke up Tuesday and said there will be a Republican nominee by tonight, that's not how anyone planned the week. We started a process, myself included, that was going to go to June 7th and believe there would be more time, and a lot of these discussions would be happening over the course of the next 40 days, they didn't. So I think we are starting now, we will start the process. I believe we are unified coming into Cleveland, coming out and committed to defeating Hillary Clinton.

BLITZER: You have other problems in the Republican Party now, there's no shortage of them. For example, we just learned Mitt Romney is not going to the Republican National Convention in July in Cleveland, John McCain is not going to go, two recent Republican presidential nominees. Neither President Bush, they won't comment or talk about Donald Trump. That's a serious slap in the face to the Republican presidential nominee.

SPICER: Well, look, last cycle former President Bush didn't attend the convention either. I'm the spokesman for the party. I would like to have high ranking Republicans there, it would be great to have them there, they're an important part. We need all the help we can to win the election, Republicans and independents, soft Democrats. We need to grow the party, not subtract it.

But at the end of the day, there are people in cycles, senator McCain being one, who are focusing on their races as the should. It happens every cycle. I was involved in a member's race in 1996 that chose not to go to San Diego.

This is part of the process. I was there in 2012 in Charlotte where several prominent senators, Claire McCaskill, Governor Tomlin, didn't show up for Barack Obama. This is part of what happens.

So I know it is a good news story, but it's the reality of people who are up for re-election.

BLITZER: Here's another news story, Republican senator from Nebraska, Ben Sasse, he put out a statement saying this, "The people deserve better than these two terrible choices," referring to Donald Trump and Hillary Clinton. "They want more choices, they're right." He wants a third party candidate to emerge to run against Donald Trump

as the Republican nomine nominee and Hillary Clinton if she becomes the Democratic nominee.

SPICER: Right. I understand it on the Democratic side, you have between Hillary Clinton who is under investigation by the FBI.

BLITZER: Ben Sasse is a Republican.

SPICER: I understand that and that's why I'm saying I agree with half of his statement. I agree with his understating that Hillary Clinton is a very flawed candidate. Most Americans don't --

BLITZER: He says Trump is a very flawed candidate.

SPICER: But at the end of the day, more voters than ever before participated in a process. That's who they chose.

I understand that we had a great number of qualified candidates, frankly, a historic number that ran this time and people passionate about the individual candidate they supported, they may have had a second choice.

But now as Republicans we need to come together, look what happened in 2008, Barack Obama went at it epically. They made up afterwards and he appointed her as secretary of state afterwards.

I think if as Republicans really think about the big prize, look at what's at stake in the election.

(CROSSTALK)

SPICER: We are two days out of this. We've got time, Wolf. I think, don't worry, going into Cleveland, this is not the conversation we will be having. I think that we're going to be unified. There's going to be a lot of excitement.

I think once people start realizing that Hillary Clinton is the alternative, we will not only be unified as a party, but we will continue to grow.

BLITZER: You have other prominent Republicans as you know that don't want a third party candidate. They say they'll vote for Hillary Clinton.

SPICER: A third party candidate is a step toward helping Hillary Clinton, bottom line. If you support a third party candidate, you might as well say, "I support Hillary Clinton." That's it. There's no other option.

BLITZER: There is another option. If it is a good third party candidate, if the third party candidate --

SPICER: No, it's not. It's silly.

(CROSSTALK) BLITZER: If that third party candidate win some electoral --

SPICER: The last time a third party candidate got an electoral vote was 1968. It is not going to happen. So, the idea of saying that there's no organization, there's no funding mechanism, and frankly, there's no consensus candidate. It is not going to happen. It's a great cocktail conversation point. But --

[18:30:03] BLITZER: I raise the point, because the former mayor of New York City, Michael Bloomberg, said he wasn't going to run, because he knew if he did he'd get some Electoral College votes, it would be thrown to the House of Representatives, no one would get 270 Electoral College votes and the Republican majority in the House would pick the Republican to be the nominee.

SPICER: There you go. OK, so under every scenario we end up with the Republican. But at the end of the day, a guy like Mike Bloomberg, who's worth billions and billions of dollars, got elected, you know, as mayor of New York City, which is no easy task, understands that he couldn't do it. So the idea that a bunch of people who are out at cocktail parties around D.C. think that they're going to pull together some magic solution and make it happen is...

BLITZER: Your message to those like Mike Salter, a former top aide to John -- Mark Salter, who says he's going to support Hillary Clinton?

SPICER: Is take some time, breathe, relax. I understand that it was a competitive primary. There was a lot of elbows thrown. I understand it.

Relax, take some time. Watch what happens. Give Donald Trump some time to show what he wants to -- how he wants to lead this party. We've got plenty of time, unlike the Democrats. But understand that Hillary Clinton is an unacceptable choice to anyone who considers himself a conservative at all.

BLITZER: Sean Spicer, the chief strategist, communications director for the Republican National -- You have a tough job up there, Sean.

SPICER: Thank you.

BLITZER: All right. Thanks very much for joining us.

The breaking news continues here on CNN. Much more coming up on the dramatic words from House speaker, Paul Ryan, saying he's not ready to support Donald Trump. Are his remarks unprecedented?

Plus, we have dramatic new video of the battle with ISIS that left a U.S. Navy SEAL dead. Did American forces have access to intelligence that could have saved his life?

(COMMERCIAL BREAK)

[18:35:00] BLITZER: Breaking news this hour. House Speaker Paul Ryan says he can't endorse Donald Trump right now. Ryan told CNN's Jake Tapper in an exclusive interview -- and I'm quoting him now -- "I am not there right now" and says Trump must first work to unify the party and express support for conservative principles.

Trump has just responded -- responded with a statement of his own, saying he's not ready to support Speaker Ryan's agenda.

Let's get some more with our national political reporter for Real Clear Politics, Rebecca Berg; our senior political correspondent, Brianna Keilar; our political commentator, S.E. Cupp; and our CNN senior political analyst, the senior editor for "The Atlantic," Ron Brownstein.

S.E., Speaker -- I guess it's a pretty startling development. I don't remember a time when we've seen anything like this develop shortly after the Republican National Committee or a Democratic National Committee announces the presumptive nominee.

But it is nothing short of stunning that today the Republican speaker of the House came out and said he is not yet willing to endorse the presumptive Republican nominee. And that is because Paul Ryan is a man of immense integrity, character and conservatism. And some of the things that Donald Trump has been saying sound very un-conservative and unconstitutional. That is an offense to Paul Ryan, who believes deeply in the causes of conservatism.

He also acknowledges that half of the Republican Party is not with Donald Trump, and that Donald Trump needs to reach those voters to actually have a chance to beat Hillary Clinton.

BLITZER: But Ron Brownstein, if that were not enough, Donald Trump then responds with this powerful statement going after Speaker Ryan. He says, "I am not ready to support Speaker Ryan's agenda. Perhaps in the future we can work together and come to an agreement about what is best for the American people. They have been treated so badly for so long that it is about time for politicians to put them first."

What a rebuke. What a response. Vintage -- I should say vintage Donald Trump, but it's pretty amazing.

RON BROWNSTEIN, CNN SENIOR POLITICAL ANALYST: This is extraordinary, unprecedented, almost unimaginable, pick your description. But in some ways it's not shocking to me in two different respects.

First, it continues a series of unprecedented, unimaginable ruptures that we have been seeing as Donald Trump has marched toward the nomination now with Bush 41 and Bush 43 saying they're not going to endorse. Mitt Romney openly condemning him.

More important, I think you can see the collision coming between Paul Ryan and Donald Trump for a while. In fact, I wrote in a column in January that the two were on a collision course, and part of it are specific issues, whether it's immigration, trade, entitlement reform, where Paul Ryan is an advocate and Donald Trump resists. But I think it is more fundamental than that, and the tipoff, Wolf,

was Paul Ryan's mention of Jack Kemp today in his statement, when he said it was the party of Lincoln, and Reagan, and Kemp. Ryan envisions a conservatism that tries to expand by applying conservative principles to the challenges facing all communities, including minority communities.

And I think he reflects the fear that what Donald Trump is leading the GOP toward is a European-style racial nationalism that is fundamentally oriented toward the grievances of alienated whites. And I think Ryan is one of many Republicans who worries about what that definition will mean for the party, whatever happens in November in terms of their long-term prospects in a rapidly diversifying country.

BLITZER: And Brianna Keilar, think about this for a moment. In a statement, in the interview he gave to Jake Tapper here on CNN, Speaker Ryan says he has questions about Donald Trump's, quote, "limited" -- where he stands about -- Donald Trump stands "on limited government, the proper role of the executive," and get this, "adherence to the U.S. Constitution." He's got questions about Donald Trump's adherence to the Constitution.

[18:40:19] BRIANNA KEILAR, CNN SENIOR POLITICAL CORRESPONDENT: You know, I agree with Ron on this. I think it's not particularly surprising. I think it's gigantic that he said this. This is big news. This is stunning in that regard, but maybe not surprising.

I think, to borrow a sort of term from budget parlance, Paul Ryan is concerned about the out years when you're talking about the Republican brand. You could argue he might be concerned, as well, about some of his own ambitions. But I would say that I think when he's worried about the Republican brand, he sees these two things as very much joined.

In fact, recently, just last week he was at Georgetown University. He had a talk there. It was moderated by S.E. It was really interesting, really revealing, where he was talking to millennials. And he said to them, "The America you want is the America we want open, diverse, and dynamic."

And so he's trying to bring about, I think, a change in the Republican brand and I think that what he's talking about is different than what we've heard Donald Trump talking about. So it would have been, quite frankly, a little odd for him to just get in line. It would have been basically taking back sort of what he said or turning on exactly what he had said.

BLITZER: Because he, you know, not that long ago, only a few days ago, we heard what the former speaker of the House, John Boehner, had to say about Donald Trump, which was pretty tough stuff. But then now, the current speaker of the House, say -- what does it say about the divisions within the Republican Party?

CUPP: It's hard to imagine they will get bridged. That said, there's a lot of Republicans who are going to be partisan -- I don't use that negatively -- who will eventually support the nominee. And who knows? Maybe Donald Trump does understand that he cannot win a general election just with this, you know, group of supporters and leaving moderates and, you know, establishment people out.

And if he does realize that, maybe he'll make some of those overtures to the people he's been insulting.

BLITZER: You saw these reports. John McCain is up for reelection. He's got a tough race in Arizona. Audio surfaced of him today say Trump could hurt him with Hispanics. This will be, he says, the race of his life. Could Trump negatively impact what are called down- ticket Republicans?

CUPP: Yes, of course. I mean, you know, Senator McCain is worried, but senators Ayotte and Toomey and Mark Kirk and Portman are really, really worried. And, you know, Republicans who care about keeping the Senate and that Supreme Court appointment have cause to be worried about Trump's effect down-ballot.

BLITZER: Rebecca, you've been doing a lot of reporting on vice- presidential picks, potentially, for Donald Trump. What are you picking up?

REBECCA BERG, REAL CLEAR POLITICS: Well, he has a few factors he's looking for. He wants to round out his ticket. That's what you always look for in a running mate. Someone who's going to make up for places where you fall short. And for him, that's definitely political experience. So he's looking for an experienced politician to sort of round out his outsider brand.

We're hearing some names thrown around at this point, but what is really interesting to me are all the people who are already taking themselves out of consideration. It's very unusual. It really speaks to the divisions in the Republican Party that people like John Kasich, Marco Rubio, Nikki Haley are already saying, "We want no part of this. Please do not consider us as a running mate."

BLITZER: Pretty amazing stuff.

You know, Ron, you wrote a pretty fascinating piece in "The Atlantic" about how white women could be the key swing vote in November. Tell us why.

BROWNSTEIN: Yes, for all the talk about the gender gap, it can obscure more than it illuminates. The fact is, Republicans have won white women in every presidential election since 1972 except one. The problem for Donald Trump is it is not enough to win them narrowly. Given the troubles that he's facing among minority voters, even if you grant him, assume that he wins the same share of white men as Ronald Reagan did in 1984, the best performance in modern times for a Republican among white men, he would still have to win 58 percent of white women to get to a national majority.

And today, he is losing among women. That 58 percent is slightly more, even, than Mitt Romney won in 2012. So it is a marker of the challenge that he faces. Even a narrow victory among white women almost certainly would ensure overall defeat in November. BLITZER: All right, guys. Thanks very much. Don't go too far away.

Important programming note to all of our viewers: the full CNN interview with Paul Ryan will air later tonight, 9 p.m. Eastern on "AC 360."

This important programming note, as well. The Democratic presidential candidate, Senator Bernie Sanders, he will be my guest, right here in THE SITUATION ROOM, tomorrow. That begins at 5 p.m. Eastern.

Just ahead, we have stunning new video of the firefight with ISIS forces that killed an American Navy SEAL and a stunning admission by the Pentagon.

(COMMERCIAL BREAK)

[18:44:32] BLITZER: Disturbing new details are emerging tonight about the death of an American Navy SEAL killed in a surprise ISIS attack in Iraq.

Our Pentagon correspondent, Barbara Starr, is working the story for us.

Barbara, some dramatic new video of the deadly gun battle also emerging. What's the latest?

BARBARA STARR, CNN PENTAGON CORRESPONDENT: New details, Wolf. You know, U.S. forces are not supposed to be in combat in Iraq or Syria. But on this day, combat came to the Navy SEALs.

(BEGIN VIDEOTAPE)

STARR (voice-over): Gunshots ring out.

[18:50:01] An American yells. An ISIS stages a surprise attack.

A raging gun battle unfolds in this video, exclusively obtained by "The Guardian."

The blurred faces U.S. Navy SEALs, alongside Kurdish Peshmerga forces in Iraq. With no protect but their white SUVs, this is the battle would kill Charles Keating. Question of whether the SEALs had access toll of the intelligence they desperately needed. And an extraordinary admission from the Pentagon press secretary.

PETER COOK, PENTAGON PRESS SECRETARY: And the forces there been able to see this attack coming, they would have responded differently to it. Perhaps this could have been avoided. That's certainly something that we're looking at carefully.

STARR: The SEALs are not supposed to be in combat. They were there to visit behind the front lines. Keating now mourned deeply by his family, was part of a quick reaction force called in to try to get the Americans out of the line of fire.

The battle had erupted suddenly. At 7:30 a.m., ISIS forces broke through the front line and reached the American positions. At 7:50, the American advisers come under fire and call for help.

At 9:32, Keating, who was part of the force called in, is hit by direct fire. He was medevaced within the hour, but his wound was not survivable.

COOK: They did not anticipate this particular strike, the kind of force that was brought to bear in this particular instance. And as a result, we saw the firefight.

STARR: As Peshmerga forces tried to retake the area, coalition aircraft rolled in, carrying out more than 30 airstrikes against ISIS positions.

(END VIDEOTAPE)

STARR: This gun battle got so serious, so violent, that even the medevac helicopters that came in to take Keating off the line of fire came under fire themselves -- Wolf.

BLITZER: All right. Barbara, thank you.

Just ahead, there's a new twist in the investigation into the death of Prince. Why members of his inner circle are now coming under some scrutiny.

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[18:46:53] BLITZER: A new twist tonight in the investigation into the death of Prince as we learn more about the role prescription pain killers may have played.

CNN's Brian Todd is working this story for us.

Brian, officials are trying to find those individuals who may have been supplying these kinds of pain killers?

BRIAN TODD, CNN CORRESPONDENT: They are, Wolf.

New information from investigators tonight. Sources telling CNN, Prince's inner circle is now under scrutiny. Officials are zeroing in on the people closest to Prince to see if any of them were runners or straw buyers for prescription drugs.

(BEGIN VIDEO CLIP)

TODD (voice-over): Tonight, investigators are intensely tracking the drugs Prince had in his possession. And who gave them to him. Law enforcement officials familiar with the case tell CNN, investigators believe Percocet is one of the drugs Prince was taking.

But they don't know if that contributed to his death. Experts say opiate pain killers are highly addictive and potentially harmful.

DR. SANJAY GUPTA, CNN CHIEF MEDICAL CORRESPONDENT: You don't want to be using these types of medications long-term. Don't work long-term. And second of all, people will start to use more and more because it's not controlling their pain.

TODD: One area investigators are honing in on tonight, Prince's inner circle, trying to determine if those closest to the superstar were intermediaries and helped him obtain prescription drugs.

MICHAEL VIGIL, FORMER DEA CHIEF OF INTERNATIONAL OPERATIONS: Obviously, they're going to look at the inner circle. They're going to look at his friends, they're going to look at family. They're going to look at the physicians he may be using.

TODD: Officials say the DEA is joining the investigation. Lending expertise about a problem called "prescription drug diversion."

(on camera): What is prescription drug diversion?

VIGIL: For example, if I were to obtain a prescription for pain medication, and I didn't use all of those pills, and I gave those to my friends, that is diversion.

TODD: And it isn't always just one person diverting the drugs to the addict. Law enforcement experts say prescription drug dependence may have a network, runners who get the meds either by prescription or in the massive black market.

Law enforcement officials tell CNN, Prince had opioids on his person and in his house when he died. And they say so far, there is no indication he had a valid prescription. Experts are worried about the epidemic of opioid abuse in America.

DR. DREW PINSKY, HLN HOST, DR. DREW: I challenge anyone to open your medicine cabinet and determine whether you have a large supply of these opiates sitting in the medicine cabinet. Most Americans do. We have excessive prescribing of this medication.

(END VIDEOTAPE)

TODD: Experts say some doctors prescribe opioids purely for profit and it has deadly consequences. Every 19 minutes in the United States, someone dies of an opioid overdose. Investigators have not yet definitively said if that is what killed Prince. Now, Prince's family is not commenting on CNN's reporting of his apparent Percocet use and the investigation of his inner circle -- Wolf.

BLITZER: This is an epidemic almost unique to America, right?

TODD: It is bizarre, Wolf. The experts in the agencies which track this say America has 5 percent of the world's population, but Americans use 80 percent of the world's prescription drugs. The stuff kills more people in the country than car crashes, Wolf.